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TDT4165: Programming Languages

# Definitions Syntax : The set of rules that defines the combinations of symbols that are recogized as sentences. Semantics : Defines what programs do when executed. Syntactic sugar

: Adds a shorthand in the syntax, but does not create a new semantic. Compiling : Source code is used to produce a executable binary which can be run on the target machine. Interpreting : The program reads the source code when run.

## Linguistic abstraction Abstraction and addition to a language, by using already existing concepts of the language _Example:_ use `proc` to define `fun`

## Programming paradigms Object oriented : Objects encapsulate data and methods. Objects send messages and execute operations on receiving messages. Imperative : The program consists of a sequence of statements which update the state of variables. Usually close to the underlying hardware. Declarative ~~programs~~ : The program specifies what needs to be done and let the language decide how it is done. Functional : Programs consist of functions that compute values based on input. Lazy execution : Expressions are not evaluated until they are needed. Concurrent : Programs are able to do several operations at the same time. Logic programming : A program is a set of logical assertions and can be used to find out if a query is true. ## Declarative programming

- stateless - independt - deterministic In other words, every time you run a declarative program with the same input (or just a declarative component) it will give you the same result (i.e. output).

### Observal declarativity

A component can be seen as declarative if the definition is, even though the implementation is not _Example:_ A database with a declarative interface. ## Higher-order programming Use procedure values in programs. (E.g. pass procedures as arguments to other procedures) __Closure__ = procedure value. Four basic operations underlie all techniques in higher order programming ### Procedural abstraction Any statement can be put into a procedure. ### Genericity The ability to pass procedure values as arguments to a procedure call. ### Instatiation The ability to return procedure values as results from a procedure call. ### Embedding

Put procedure values in data structures # Oz ## Functions and procedures ## Higher order functions ## Dataflow ## Records ## Cncurrency ## Lazy evaluation ## Streams ## Explicit state ## Encapsulation ## Inheritance ## Pattern Matching ## Declarativity ## Non-determinism